Exhaust systems for internal combustion engines are known to have mufflers and exhaust gas treatment devices, for example, catalytic converters and particle filters. An exhaust gas treatment device used for this purpose may be specialized for a single exhaust gas treatment function. Combined devices are likewise known, in which at least two different functions are implemented, for example, a particle filter in combination with a catalytic converter, and a muffling effect may additionally be integrated as well. Provisions may be made especially in case of more complex exhaust gas treatment devices, which contain a particle filter element, for the particle filter element to be replaced at least once during the service life of the exhaust system. It is necessary for this to arrange the particular particle filter element replaceably in the exhaust gas treatment device. This correspondingly also applies, in principle, to other exhaust gas treatment elements, such as SCR catalytic converters, oxidation-type catalytic converters and other catalytic converters.
For this purpose, an exhaust gas treatment device may have a housing, in which at least one mounting pipe is arranged, which contains a mounting space. Further, the exhaust gas treatment device may have at least one cartridge, which is arranged replaceably in the mounting space and which has a cartridge pipe as well as at least one exhaust gas treatment element arranged in the cartridge pipe. To replace the exhaust gas treatment element, the entire cartridge can simply be pulled out of the mounting pipe, with the housing opened, and replaced with a new cartridge, which is then pushed into the mounting pipe. The use of such cartridges simplifies the replacement of the particular exhaust gas treatment element, because especially the mounting of the particular exhaust gas treatment element within the cartridge pipe can be embodied within the cartridge in a conventional manner, for example, by means of a radially pressed mounting mat. In particular, a conventional canning of the exhaust gas treatment element, mounting mat and cartridge pipe can thus be carried out in order to manufacture such a cartridge.
The circumstance that a bypass flow, which bypasses an exhaust gas flow path routed through the particular exhaust gas treatment element and is intended for the exhaust gas purification function, will develop radially between the cartridge pipe and the mounting pipe during the operation of the exhaust gas treatment device is problematic in such exhaust gas treatment devices. On the one hand, the efficiency of the exhaust gas purification effect is reduced in this manner. On the other hand, contaminants, which make it difficult to remove the cartridge from the mounting space in case of maintenance, may be deposited as a result in an annular space formed radially between the cartridge pipe and the mounting pipe.